Lignocellulosic biomass is an abundant, renewable resource, but the structural and chemical complexity of biomass acts as a hindrance in its effective utilization for cellulosic ethanol production. Hence, effective pretreatment is always necessary to remove the surrounding matrix of lignin prior to the enzymatic hydrolysis. Pretreatment of rice straw by Pleurotus florida was found to be effective and resulted in 49% lignin degradation, whereas fungus along with grape leaves resulted in 99% lignin degradation. This method not only explores a pathway for utilizing the solid agro waste but also results in a value-added product of edible mushrooms that has proved to be the best pretreatment technology for ethanol production. FTIR and SEM analysis confirmed the structural transformation taking place during the pretreatment. The components of grape leaves were also analyzed using GC-MS.